Methods have been developed for measuring pulmonary resistance as a function of lung volume. We are in the process of relating changes in this relationship in awake and anesthetized dogs to changes in lung pressure volume behavior. We are also expanding studies relating changes in lung mechanics to general anesthesia. Particular attention is going to be paid to the general anesthetic agents and the concentrations of the agents both in the inspired gas and in the blood. This will expand upon work previsouly done in this laboratory using barbiturate anesthesia. We plan to study various types of artificial ventilation and their effects on lung mechanics in awake and anesthetized dogs. We propose to determine the presence and distribution of H1 and H2 receptors in the airways of dogs lungs. Excised airways will be studied and the presence and location of the two receptors will be studied by specific agonists and antagonists.